Respiration rate refers to the number of breathing cycles per minute. It is one of the important vital signs and frequently measured during the diagnosis and treatment of many pulmonary dysfunctions. Typically, in healthy adults the respiration rate ranges from 5 to 35 breaths per minute. The deviation of respiration rate from this usual range is indicative of pulmonary diseases like asthma, chronic obstructive pulmonary disease, tuberculosis, respiratory-tract infection, etc. Further, abnormally high respiration rate is an indication of pneumonia in children or tissue hypoxia associated to sleep apnea. Such pulmonary diseases cause about 18% of human deaths in the world. Often irregularities in respiration rate are also indicative of cardiac malfunctioning. Respiration rate is routinely measured for clinical diagnosis in many primary health care centers. Besides, measurement of respiration rate in an intensive care unit (ICU) directly ascertains whether the patient is breathing or not. Moreover, measurement of respiration rate can also be used for the analysis of human emotions such as anger or stress.
There exist a number of techniques for respiration rate measurement, including spirometry, impedance pneumography and plethysmography. However, these methods employ the use of contact based probes in the forms of leads or straps. Such contact-based methods are often prohibitive in many situations. They not only cause discomfort or irritation, particularly to sensitive skins, often patients change their normal breathing pattern during the monitoring with such contact-based methods. It can also be difficult to use such methods in neonates ICU or home monitoring. Further, during gated radiography it is not possible to use contact based measurements as they directly interfere with the radiography. Due to these reasons, non-contact RR measurement is becoming an emerging and immensely important problem in bio-medical engineering community.
Accordingly, what is needed in this art are sophisticated systems and methods for determining a respiration rate from a video of a subject breathing.